In-file Templates

NOTE: Sinatra will automaticly load any in-file-templates in the source
file that first required sinatra. If you have in-file-templates in another
source file you will need to explicitly call +use_in_file_templates! on
main in that file.

It's also possible to define named templates using the top-level
template method:

template :layout do
"%html\n =yield\n"
end
template :index do
'%div.title Hello World!'
end
get '/' do
haml :index
end

If a template named “layout” exists, it will be used each time a template
is rendered. You can disable layouts by passing :layout =>
false.

get '/' do
haml :index, :layout => !request.xhr?
end

Helpers

Use the top-level helpers method to define helper methods for use
in route blocks and templates:

helpers do
def bar(name)
"#{name}bar"
end
end
get '/:name' do
bar(params[:name])
end

Filters

Before filters are evaluated before each request within the context of the
request and can modify the request and response. Instance variables set in
filters are accessible by routes and templates.

before do
@note = 'Hi!'
request.path_info = '/foo/bar/baz'
end
get '/foo/*' do
@note #=> 'Hi!'
params[:splat] #=> 'bar/baz'
end

Halting

To immediately stop a request during a before filter or route use:

halt

You can also specify a body when halting …

halt 'this will be the body'

Set the status and body …

halt 401, 'go away!'

Passing

A route can punt processing to the next matching route using the
pass statement:

get '/guess/:who' do
pass unless params[:who] == 'Frank'
"You got me!"
end
get '/guess/*' do
"You missed!"
end

The route block is immediately exited and control continues with the next
matching route. If no matching route is found, a 404 is returned.

Configuration and Reloading

Sinatra supports multiple environments and reloading. Reloading happens
before each request when running under the :development
environment. Wrap your configurations (e.g., database connections,
constants, etc.) in configure blocks to protect them from
reloading or to target specific environments.

Run once, at startup, in any environment:

configure do
...
end

Run only when the environment (RACK_ENV environment variable) is set to
:production.

configure :production do
...
end

Run when the environment (RACK_ENV environment variable) is set to either
:production or :test.

configure :production, :test do
...
end

Error handling

Error handlers run within the same context as routes and before filters,
which means you get all the goodies it has to offer, like haml,
erb, halt, etc.

Not Found

When a Sinatra::NotFound exception is raised, or the
response's status code is 404, the not_found handler is
invoked:

not_found do
'This is nowhere to be found'
end

Error

The error handler is invoked any time an exception is raised from
a route block or before filter. The exception object can be obtained from
the 'sinatra.error' Rack variable:

error do
'Sorry there was a nasty error - ' + env['sinatra.error'].name
end

Custom errors:

error MyCustomError do
'So what happened was...' + request.env['sinatra.error'].message
end

Then, if this happens:

get '/' do
raise MyCustomError, 'something bad'
end

You get this:

So what happened was... something bad

Sinatra installs special not_found and error handlers when running under
the development environment.

Mime types

When using send_file or static files you may have mime types
Sinatra doesn't understand. Use mime to register them by file
extension:

mime :foo, 'text/foo'

Rack Middleware

Sinatra rides on Rack, a minimal
standard interface for Ruby web frameworks. One of Rack's most
interesting capabilities for application developers is support for
“middleware” – components that sit between the server and your application
monitoring and/or manipulating the HTTP request/response to provide various
types of common functionality.

Sinatra makes building Rack middleware pipelines a cinch via a top-level
use method:

require 'sinatra'
require 'my_custom_middleware'
use Rack::Lint
use MyCustomMiddleware
get '/hello' do
'Hello World'
end

The semantics of use are identical to those defined for the Rack::Builder
DSL (most frequently used from rackup files). For example, the use
method accepts multiple/variable args as well as blocks:

Rack is distributed with a variety of standard middleware for logging,
debugging, URL routing, authentication, and session handling. Sinatra uses
many of of these components automatically based on configuration so you
typically don't have to use them explicitly.

Testing

The Sinatra::Test module includes a variety of helper methods for testing
your Sinatra app. Sinatra includes support for Test::Unit, test-spec,
RSpec, and Bacon through separate source files.

Contributing

Tools

Besides Ruby itself, you only need a text editor, preferably one that
supports Ruby syntax hilighting. VIM and Emacs are a fine choice on any
platform, but feel free to use whatever you're familiar with.

Sinatra uses the Git source code management system. If you're
unfamiliar with Git, you can find more information and tutorials on git.or.cz/ as well as git-scm.com/. Scott Chacon created a great
series of introductory screencasts about Git, which you can find here: www.gitcasts.com/

Using Edge Sinatra in Your App

Contributing a Patch

There are several ways to do this. Probably the easiest (and preferred) way
is to fork Sinatra on GitHub (github.com/bmizerany/sinatra),
push your changes to your Sinatra repo, and then send Blake Mizerany
(bmizerany on GitHub) a pull request.

You can also create a patch file and attach it to a feature request or bug
fix on the issue tracker (see below) or send it to the mailing list (see
Community section).